UniChrom-DHA

The automatic gas chromatographic system UniChrom-DHA for the detailed hydrocarbon analysis (DHA) of various petroleum fractions and products has been developed.
Samples of gasoline are analysed by temperature programmed gas chromatograph on a high-resolution capillary column which separates hydrocarbons in order of their boiling points. Individual components are identified comparing their Kovats or linear retention indices with a library of 330 components. Then all the major gasoline standardised specifications are calculated from the obtained DHA data. As the result of single chromatographic petrol sample analysis (about 120 min) it is possible to determine the next certificate characteristics:

• ASTM D6730 - 01(2011) Standard Test Method for Determination of Individual Components in Spark Ignition Engine Fuels by 100–Metre Capillary (with Precolumn) High-Resolution Gas Chromatography
• Detailed hydrocarbon and fractions contents (ASTM D5134, GOST 6994 and ASTM D5580, GOST 8997 and GOST 2070),
• Contents of aromatic components ( GOST 6994 and ASTM 5580),
• Contents of olefin components ( GOST 8997 and 2070),
• Fractional content (GOST 2177 and ASTM D86),
• Detonation stability expressed in terms of research octane number RON (GOST 8226 and ASTM 2699),
• Detonation stability expressed in terms of motor octane number MON ( GOST 511 and ASTM 2700),
• Saturated vapor pressure ( GOST 1756-52 and ASTM 2889),
• Density (GOST 3900 and ASTM 4052)

History of development

In April 2001 the Laboratory of Analytical Researches (LAR) of Institute of Nuclear Problems of the Belarus State University was accredited in Testing Laboratories State Quality Assurance System for independence and technical competence. Accreditation Attest Nr BY/112.02.1.0.0384. Registration date 09 April 2001. Certificate valid till 09 April 2004. For working period have carried over 50 petrol analysis related to petrol quality.
Laboratory of Analytical Researches is ready for taking DHA analysis and petrol quality determination.
In the case of your company interest, LAR can supply with corresponding analytical equipment, methodical support and employee training.

Chromatographic System

Chromatographic data can be obtained directly from GC under UniChrom control or loaded from data files, which format is supported by UniChrom.

Basic requirements to the DHA chromatographic system:

• Can handle 100m 0.25 I.D. capillary columns
• Can handle up to 500 ml/min split flow
• Can handle up to 400 kPa inlet pressure.
• Oven temperature in range 35 .. 350C with 0.1 precission with high repeatabilty
• Data collection rate 20Hz and more

Shipping content of UniChrom-DHA

• Service (calculation module) UniChrom-DHA
• Identification library (chromatogram workbook) for end-user GC system. It is required the adaptation of GC identification library for selected GC system
• Compound library (data base) for DHA analysis
• Samples of commercial petrol used for method attestation
• Additional service modules for compound name spell-checking and avoiding multiple identification (different compounds with same name)

UniChrom-DHA service

UniChrom-DHA is the plug-in module expanding the UniChrom system. The module is not intended to work without UniChrom system.

Steps of DHA analysis

Chromatogram integration

Compound identification

DHA-parameters calculations

Results representation

Distillation curve data, obtained at the MS Excel sheet allow immediately build distillation curve (fractional content).

Fractional content curve obtained using DHA data. Each point represent the persentage of hydrocarbons boiled in specified temperature range.